"The former House speaker said his campaign went through his documents three times to make sure he paid a 31 percent rate, but said he would need to check whether that was only federal or both federal and state taxes.

"'We're pulling together the documents,' he added. 'We hope to get it out sometime tomorrow. ... And we'll release 2011 as soon as we put it together.'"

As Mark noted, yesterday, all of this comes as Romney is being pressured to release his income tax returns. Romney at first refused, but recently, he's relented and said he would release them closer to April.

Today, New Jersey Gov. Chris Christie, who was urged to run by many conservatives early in the primary race, said Romney should release his returns before April.

"I would say if you have tax returns to put out, you know, you should put them out sooner rather than later because it's always better in my view to have complete disclosure, especially as the front-runner," Christie said on NBC's Today Show, according to CNN.

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